• Title/Summary/Keyword: 공간 필터

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Image Reconstruction Using Poisson Model Screened from Image Gradient (이미지 기울기에서 선별된 포아송 모델을 이용한 이미지 재구성)

  • Kim, Yong-Gil
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.18 no.2
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    • pp.117-123
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    • 2018
  • In this study, we suggest a fast image reconstruction scheme using Poisson equation from image gradient domain. In this approach, using the Poisson equation, a guided vector field is created by employing source and target images within a selected region at the first step. Next, the guided vector is used in generating the result image. We analyze the problem of reconstructing a two-dimensional function that approximates a set of desired gradients and a data term. The joined data and gradients are able to work like modifying the image gradients while staying close to the original image. Starting with this formulation, we have a screened Poisson equation known in physics. This equation leads to an efficient solution to the problem in FFT domain. It represents the spatial filters that solve the two-dimensional screened Poisson model and shows gradient scaling to be a well-defined sharpen filter that generalizes Laplace sharpening. We demonstrate the results using a discrete cosine transformation based this Poisson model.

New separation technique of regional-residual gravity anomaly using geostatistical spatial filtering (공간필터링을 이용한 중력이상의 광역-잔여 이상 효과 분리)

  • Rim, Hyoung-Rae;Park, Yeong-Sue;Lim, Mu-Teak;Koo, Sung-Bon;Lee, Young-Chal
    • 한국지구물리탐사학회:학술대회논문집
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    • pp.155-160
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    • 2006
  • In this paper, we propose a spatial filtering scheme using factorial kriging, one of geostatistical filtering methodin order to separate regional and residual gravity anomaly. This scheme is based on the assumption that regional anomalies have longer distance relation and residual anomalies have effected on smaller range. We decomposed gravity anomalies intotwo variogram models with long and short effectiveranges by means of factorial kriging. And decomposed variogram models produced the regional and residual anomalies. This algorithm was examined using by a synthetic gravity data, and applied to a real microgravity data to figure out abandoned mineshaft.

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Direction-of-Arrival Estimation in Broadband Signal Processing : Rotation of Signal Subspace Approach (광대역 신호 처리에서의 도래각 추정 : Rotation of Signal Subspaces 방법)

  • Kim, Young-Soo
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.7
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    • pp.166-175
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    • 1989
  • In this paper, we present a method which is based on the concept of the rotation of subspaces. This method is highly related to the angle (or distance) between subspaces arising in many applications. An effective procedures is first derived for finding the optimal transformation matrix which rotates one subspace into another as closely as possible in the least squares sense , and then this algorithm is applied to the solution to general direction-of-arrival estimation problem of multiple broadband plane waves which may be a mixture of incoherent, partially coherent or coherent. In this typical application, the rotation of signal subspaces (ROSS) algorithm is effectively developed to achieve the high performance in the active systems for the case in which the noise field remains invariant with the measurement of the array spectral density matrix (or data matrix). It is not uncommon to observe this situation in sonar systems. The advantage of this techniques is not to require the preliminary processing and spatial prefiltering which is used in Wang-Kaveh's CSS focusing method. Furthermore, the array's geometry is not restricted. Simulation results are presented to illustrate the high performance achieved with this new approach relative to that obtained with Wang-Kaveh's CSS focusing method for incoherent sources and forward-backward spatial smoothed MUSIC for coherent sources including the signal eigenvector method (SEM).

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The Intrusion Sensor Using the Variations of Speckle Patterns (스페클 패턴을 이용한 침입자 센서)

  • Eom, Yeon-Sik;Kim, Yo-Hui;Yang, Seung-Guk;O, Sang-Gi;Kim, In-Su;Park, Jae-Hui;Gang, Sin-Won
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.38 no.3
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    • pp.236-241
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    • 2001
  • The speckle pattern is formed by laser light from a multimode optical fiber. The speckle fluctuation is the result of interference among propagation modes when the optical fiber is subjected to a mechanical perturbation at any point along its length. The experiments were carried on for the study of the feasibility of producing an intrusion detection system using the speckle fluctuation. The speckle fluctuation signals were monitored at real time by an oscilloscope which was connected with a rectifier and a FVC. We used a jig as a PD holder to improve the sensitivity of speckle phenomena and simplify its structure. So we can know the time and magnitude of perturbation.

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3D Adaptive Bilateral Filter for Ultrasound Volume Rendering (초음파 볼륨 렌더링을 위한 3차원 양방향 적응 필터)

  • Kim, Min-Su;Kwon, Koojoo;Shin, Byeoung-Seok
    • Journal of Korea Game Society
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    • v.15 no.2
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    • pp.159-168
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    • 2015
  • This paper introduces effective noise removal method for medical ultrasound volume data. Ultrasound volume data need to be filtered because it has a lot of noise. Conventional 2d filtering methods ignore information of adjacent layers and conventional 3d filtering methods are slow or have simple filter that are not efficient for removing noise and also don't equally operate filtering because that don't take into account ultrasound' sampling character. To solve this problem, we introduce method that fast perform in parallel bilateral filtering that is known as good for noise removal and adjust proportionally window size depending on that's position. Experiments compare noise removal and loss of original data among average filtered or biliteral filtered or adaptive biliteral filtered ultrasound volume rendering images. In this way, we can more efficiently and correctly remove noise of ultrasound volume data.

Performance analysis of DOA estimation and beamforming in 3-dimensional array antenna for GPS receiver (GPS 수신기를 위한 3 차원 배열 안테나의 도래각 추정 및 빔 형성 성능 분석)

  • Lee, Chong-Hyun;Kim, Suk-Joong;Lim, Seung-Gag
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.4
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    • pp.88-94
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    • 2007
  • This paper deals with the performance analysis of 3-dimensional array antenna by DOA estimation and beamforming in GPS receiver for performance improvement by interference elimination. The array antenna in GPS receiver can improve the system performance by estimating DOA of arriving signal direction, making the main beam for desired direction and elimate the jammer signal by nulling while keeping the GPS signal direction by spatial filtering. In this paper, we propose five types of 3-dimensional array antenna and analyze the estimation error via MUSIC algorithm which is used for the estimation of DOA of arrived signal and beamforming performance. In analyzing DOA performance, we measure DOA estimation error, while in analyzing beamformig performance, we measure BER. In beamforming performance analyzing, we use various jammer power and the existence of GPS signal and angle spread. By performing through the computer simulation, Curved (B) 7-element antenna in proposed 3-dimensional array antenna exhibits the superior performance in the DOA estimation, estimation error, BER characteristic and angle spread compared to the rest four array antenna types.

Image noise reduction algorithms using nonparametric method (비모수 방법을 사용한 영상 잡음 제거 알고리즘)

  • Woo, Ho-young;Kim, Yeong-hwa
    • The Korean Journal of Applied Statistics
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    • v.32 no.5
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    • pp.721-740
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    • 2019
  • Noise reduction is an important field in image processing and requires a statistical approach. However, it is difficult to assume a specific distribution of noise, and a spatial filter that reflects regional characteristics is a small sample and cannot be accessed in a parametric manner. The first order image differential and the second order image differential show a clear difference according to the noise level included in the image and can be more clearly understood using the canyon edge detector. The Fligner-Killeen test was performed and the bootstrap method was used to statistically check the noise level. The estimated noise level was set between 0 and 1 using the cumulative distribution function of the beta distribution. In this paper, we propose a nonparametric noise reduction algorithm that accounts for the noise level included in the image.

A Study for Introducing a Method of Detecting and Recovering the Shadow Edge from Aerial Photos (항공영상에서 그림자 경계 탐색 및 복원 기법 연구)

  • Jung, Yong-Ju;Jang, Young-Woon;Choi, Yun-Woong;Cho, Gi-Sung
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.24 no.4
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    • pp.327-334
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    • 2006
  • The aerial photos need in a simple object such as cartography and ground cover classification and also in a social objects such as the city plan, environment, disaster, transportation etc. However, the shadow, which includes when taking the aerial photos, makes a trouble to interpret the ground information, and also users, who need the photos in their field tasks, have a restriction. Generally the shadow occurs by the building and surface topography, and the detail cause is by changing of the illumination in an area. For removing the shadow this study uses the single image and processes the image without the source of image and taking situation. Also, applying the entropy minimization method it generates the 1-D gray-scale invariant image for creating the shadow edge mask and using the Canny edge detection creates the shadow edge mask, and finally by filtering in Fourier frequency domain creates the intrinsic image which recovers the 3-D color information and removes the shadow.

Performance analysis of DoA estimation algorithm using a circular array antenna (원형 배열 안테나의 DoA 추정 알고리즘 성능 분석)

  • Lim, Seung-Gag;Kang, Dae-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.2
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    • pp.395-400
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    • 2008
  • This paper relates to the performance analysis of DoA estimation algorithm in 2-dimensional circular array antenna for the receiving of GPS signal which is used for the performance improvement by elimination of jammer signal. By performing the spatial filtering after the DoA estimation in array antenna, the quality of receiving signal can improve by the nulling of jammer signal from the undesired direction and the forming of beam from the desired direction. In this paper, the MUSIC and MinNorm algorithm used for DoA estimation were applied after fixing the angle and power of jammer signal in 4 element and 7 element circular array antenna. In order to performance analysis, the estimation result and estimation error were computed by computer simulation. As a result, the MUSIC and MinNorm were fairly good in azimuth and elevation angle estimation of DoA in case of good signal to noise ratio and the MUSIC has better performance compared to MinNorm in case of poor signal to noise ratio.

Multibeam-based Subspace Approach for Code Acquisition in Antenna Array DS-CDMA Systems (안테나 어레이 DS-CDMA 통신 시스템에서 코드 동기 획득을 위한 다중 빔 기반의 부분공간 접근 방법)

  • Kim, Sang-Choon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.6
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    • pp.1167-1173
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    • 2005
  • In this paper, the use of an antenna array is considered for code timing acquisition of DS-CDMA signals. The probabilities of acquisition are evaluated by applying multiple narrow fixed-beams to the conventional MUSIC acquisition approach in the multiuser environment on the time-varying Rayleigh fading channel. Each fixed-beam for spatial filtering is dedicated to an individual angular sector that is formed by dividing the entire angular domain by the number of antenna elements. The fixed-beams with a capability of interference suppression provide the additional degrees of freedom,. Hence, the multibeam-based MUSIC estimator can be used to synchronize to more users than the conventional MUSIC algorithm for one antenna. The multibeam-based subspace method is evaluated to significantly improve the performance of a single antenna based MUSIC technique in multiuser scenarios.